Four-Channel Microstrip based RF Switchable Filter for S-band Radar Applications

Nowadays, electronic countermeasure (ECM) devices are widely used to mislead early warning radars. In an ECM system, an RF filter is a vital component to define the band of operation. In this work, a four-channel switchable bandpass filter (BPF) in S-band with low insertion loss, promising isolation, and high-power handling capability is presented. For this, a microstrip-based open-loop ring resonator is designed to collect the jamming signals, coming from the foe, need to be identified and intercepted adequately. The proposed switchable BPF is having frequencies 2.2, 2.4, 2.6, and 2.8 GHz. A T-shaped combiner is also designed to act as a frequency combiner. At each channel, reasonable bandwidth
$\leq 140$
MHz with an insertion loss (S
21
) < 2.0 dB is achieved, while the isolations among the channels are better than 33 dB.